A race is observed when cros_ec_lpc and cros-ec-keyb are all built as modules. cros_ec_lpc is cros-ec-keyb's parent. However, they can be probed at the same time. Example: + -----------------------------------------------------------------+ | Some init process (e.g. udevd) | deferred_probe_work_func worker | + -----------------------------------------------------------------+ | Probe cros-ec-keyb. | | | - Decide to defer[1]. | | | | A device bound to a driver[2]. | | Probe cros_ec_lpc. | | | - Init the struct[3]. | | | | Retry cros-ec-keyb from the | | | deferred list[4]. | | | - Won't defer again as [3]. | | | - Access uninitialized data in | | | the struct. | | - Register the device. | | + -----------------------------------------------------------------+ [1] https://elixir.bootlin.com/linux/v6.16/source/drivers/input/keyboard/cros_ec_keyb.c#L707 [2] https://elixir.bootlin.com/linux/v6.16/source/drivers/base/dd.c#L405 [3] https://elixir.bootlin.com/linux/v6.16/source/drivers/platform/chrome/cros_ec_lpc.c#L644 [4] https://elixir.bootlin.com/linux/v6.16/source/drivers/base/dd.c#L418 Note that the device link[5] can't help as in the observed environment, the devices are already added via device_add()[6]. [5] https://www.kernel.org/doc/html/latest/driver-api/device_link.html#usage [6] https://elixir.bootlin.com/linux/v6.16/source/drivers/acpi/acpi_platform.c#L177 The series fixes the issue by ensuring the struct is ready for accessing before continuing to probe cros-ec-keyb. The 1st - 3rd patches are preparatory steps to allow the per-device lock can be used even if the struct cros_ec_device is unregistered. The 4th patch introduces a new flag `registered` and use the lock for protecting the flag. The 5th patch defers probe if the struct cros_ec_device is not ready yet. Tzung-Bi Shih (5): platform/chrome: Centralize cros_ec_device allocation platform/chrome: Centralize common cros_ec_device initialization platform/chrome: cros_ec: Separate initialization from cros_ec_register() platform/chrome: cros_ec: Add a flag to track registration state Input: cros_ec_keyb - Defer probe until parent EC device is registered drivers/input/keyboard/cros_ec_keyb.c | 6 ++ drivers/platform/chrome/cros_ec.c | 85 ++++++++++++++------- drivers/platform/chrome/cros_ec.h | 3 + drivers/platform/chrome/cros_ec_i2c.c | 9 +-- drivers/platform/chrome/cros_ec_ishtp.c | 6 +- drivers/platform/chrome/cros_ec_lpc.c | 6 +- drivers/platform/chrome/cros_ec_proto.c | 15 ++++ drivers/platform/chrome/cros_ec_rpmsg.c | 6 +- drivers/platform/chrome/cros_ec_spi.c | 7 +- drivers/platform/chrome/cros_ec_uart.c | 6 +- include/linux/platform_data/cros_ec_proto.h | 18 ++++- 11 files changed, 103 insertions(+), 64 deletions(-) -- 2.51.0.268.g9569e192d0-goog
